Fatty acids play important physiological functions. They are the building blocks of phospholipids and glycolipids, crucial components of cell membranes. Fatty acids are the best biological fuel molecules, capable of yielding more than twice as much energy per gram as produced by carbohydrate or protein. Fatty acids directly affect the functions of many proteins through covalent modifications of such proteins. Fatty acids also affect membrane fluidity and associated cellular processes. Fatty acids are also involved in gene regulation, as such may be used to optimize expression of certain genes. Fatty acids' derivatives are also important hormones and biological messengers, e.g., prostaglandins, thromboxanes, leukotrienes, lipoxins, and resolvins. These hormones and messengers affect a broad range of physiological functions such as vasal dilation, platelets aggregation, pain modulation, inflammation, and cell growth.
The human and animal bodies synthesize many kinds of fatty acids of various length of the carbon chain, with various numbers and locations of double bonds. The addition of double bonds into a fatty acid chain converts it into an unsaturated fatty acid, which play significant roles in physiological functions. One way of tracking the location of the double bond in an unsaturated fatty acid molecule is by its distance from the distal carbon, i.e., the omega-carbon. For example, the 18-carbon oleic acid, which has a double bond at the 9th carbon from the omega position, is called omega-9 fatty acid. Table 1 below describes various unsaturated fatty acid groups named according to their double bond locations relative to the omega position:
TABLE 1General Descriptions of Some Fatty AcidsName ofStarting Molecule Fatty AcidGeneral Formulafor BiosynthesisOmega-3CH3—CH2—CH═CH—R—COOHAlpha-Linolemic AcidOmega-6CH3—(CH2)4—CH═CH—R—COOHLinoleic AcidOmega-7CH3—(CH2)5—CH═CH—R—COOHPalmitoleic AcidOmega-9CH3—(CH2)7—CH═CH—R—COOHOleic Acid
As shown in the table above, Linoleic acid (LA) and Alpha-linolenic Acid (ALA) are the precursors for all omega-6 and omega-3 fatty acids. It is well established that LA and ALA are “essential” fatty acids. They must be supplied in the diet because the human and other mammalians cannot synthesize them from other sources. Dietary deficiency or excess of the two essential fatty acids may cause many illnesses. It is also well known that LA and ALA share the same metabolic pathways, and that the excess of one can increase the need for, or create a deficiency of, the other. Along with LA and ALA, certain other fatty acids, such as Oleic acid and certain saturated fatty acids are also considered important for human nutrition even though the body can make them. The latest science also shows evidence that non-essential fatty acids though beneficial in optimal quantities, can interfere with the activity and metabolism of essential fatty acids when in excess, and that the quantity of dietary fat can also influence the metabolism of fatty acids. ALA is known to be preferentially metabolized by the human body depending on the amount of the other fatty acids present in the diet.
Evidence also shows that antioxidants, phytochemicals, microorganisms, vitamins and minerals, other dietary factors including proteins and carbohydrates, and hormones and genes also play a role in metabolism of essential fatty acids. Furthermore, human studies have identified that males and females appear to differ in their ability to metabolize essential fatty acids. It has been suggested that sex hormones play a role in these differences. Molecules of polyunsaturated fatty acids have a zigzag-like structure because of the double bonds. Because they are flexible and do not pack tightly, they stay fluid even at cold temperatures and collectively lend flexibility to tissues. Hence, in colder climates the human body benefits from greater amounts of polyunsaturated fatty acids. However, the greater the number of double bonds in a lipid molecule, the greater the susceptibility to per-oxidation, which may be associated with a number of diseases and may accelerate aging. This is another reason for cautious consumption of polyunsaturated fatty acids.
Numerous studies provide evidence for the prophylaxis and treatment of medical conditions using supplementation with omega-3 fatty acids and recommendations to reduce omega-6 fatty acid consumption. The medical conditions implicated include menopause, cardiovascular diseases, mental disorders, neural disorders, musculoskeletal disorders, endocrine disorders, cancer, digestive system disorders, symptoms of aging, viral infections, bacterial infections, obesity, overweight, renal diseases, pulmonary disorders, ophthalmologic disorders, dermatological disorders, sleep disorders, dental diseases, and the diseases of the immune system including autoimmunity. For example, U.S. Pat. No. 5,780,451 taught lipid formulations for patients with ulcerative colitis, which include omega-3, omega-6, and omega-9 fatty acids. The omega-3 fatty acid content in these lipid formulations was significantly high. Similarly, a recently published U.S. patent application, US2008/0039525, disclosed lipid compositions used for diabetic patients, which contained omega-3, omega-6, and omega-9 fatty acids, with the specific ratio of omega-6 to omega-3 being between 0.25:1 to 3:1.
The traditional emphasis on increasing omega-3 fatty acids and reducing omega-6 fatty acids consumption often does not result in satisfactory relieves because of the uncertainties introduced by dietary and demographic factors. Accordingly, improved methods and treatments, using improved lipid compositions, for the medical conditions and for prophylaxis are still needed. In fact, on Jan. 26, 2009, for the first time the American Heart Association issued an advisory to correct the perception that omega-6 fatty acids are unhealthy. Harris et al., Omega-6 Fatty Acids and Risk and Cardiovascular Disease. A Science Advisory From the American Heart Association Nutrition Subcommittee of the Council on Nutrition, Physical Activity, and Metabolism; Council on Cardiovascular Nursing; and Council on Epidemiology and Prevention. Circulation. 2009;119;902-907. The current methodologies are contusing for the consumer, hence lead to over consumption or under consumption of critical nutrients with major health consequences.